The proposed research aims to develop, refine, test/evaluate, and apply new methods of analyzing statistical data on marital fertility for the purpose of (a) measuring the extent of fertility control exercised by members of given marriage cohorts in historical or contemporary circumstances which preclude eliciting such information by direct survey questionnaire methods, and (b) identifying and gauging the qualitative importance of factors determining child=spacing and birth-averting behavior at the micro level from the analysis of birth histories. One set of methods to be developed is referred to as cohort parity analysis (CPA), and yields estimates of the proportion controlling and the distribution of controllers by parity, by comparing information from model parity distributions fo "natural fertility" populations with corresponding statistics derived from given, historical parity distributions. Further development of maximum likelihood estimators for these proportions will permit corrections for censoring biases in observed completed parity distributions, due to parity-related differentials in rates of marriage dissolution experienced by women in both the preporductive and post-reporductive phases of their lives. Another set of methods is based on a statistical modelling approach to analyzing birth intervals, either on an order-specific basis or in sequences, allowing for censoring, truncation, unobserved heterogeneities affecting fertility, and the endogeneity of time-varying individual characteristics o the couple and initial conditions affecting the waiting time distribution. Microdemographic simulations, and tests on data sets in which there is extraneous information on the use or non-use of fertility control methods, will be used to evaluate the foregoing methods of analysis. Applications will be made in studies of several large data sets, derived from censuses and genealogies referring to the U.S. population between 1800 and 1940, and from family reconstitutions of rural French villages in 1740-1829. Tests will be made of various hypotheses about the timing and determinants of the transition from social to individual modes of fertility regulation, as part of the Stanford Project on the History of Fertility Control's program of comparative studies of fertility transitions.